SBNation has uncovered a fan video of what is likely the incident. The video, uploaded (in horrible quality) by yfrog user ChaneHNL, shows Johnson making one of the many international “F you” signs as Fire fans taunt him — not the middle finger, in this case, but the closed-fist arm pump. (I have no idea how to describe that.)

“I sincerely apologize to the Chicago fans, my teammates, MLS, and the Sounders’ supporters for my actions and poor judgment I used on Saturday,” Johnson said in a statement Tuesday. “It was a very emotional game and I let my emotions get the best of me. That is not acceptable and I take full responsibility for my actions. I am truly sorry this took attention away from the success of our team after a great win in Chicago.”

The amount of Major League Soccer’s fine against Johnson was undisclosed.